Active matrix display device

ABSTRACT

In order to provide an active matrix display device in which parasitic capacitance or the like is suppressed by forming a thick insulating film around an organic semiconductor film and disconnection or the like does not occur in the opposing electrode formed on the upper layer of the thick insulating film, in an active matrix display device, first, a bank layer composed of a resist film is formed along data lines and scanning lines, and by depositing an opposing electrode of a thin film luminescent element on the upper layer side of the bank layer, capacitance that parasitizes the data lines can be suppressed. Additionally, a discontinuities portion is formed in the bank layer. Since the discontinuities portion is a planar section which does not have a step due to the bank layer, disconnection of the opposing electrode does not occur at this section. When an organic semiconductor film is formed by an ink jet process, a liquid material discharged from an ink jet head is blocked by the bank layer.

This is a Divisional Application of application Ser. No. 11/905,591filed Oct. 2, 2007, which is a Divisional of application Ser. No.10/442,057 filed May 21, 2003, which is a Continuation of applicationSer. No. 09/993,565 filed Nov. 27, 2001, which is a Divisional ofapplication Ser. No. 09/284,774 filed Apr. 20, 1999, which is a NationalPhase of Application No. PCT/JP98/03663 filed Aug. 18, 1998. The entiredisclosures of the prior applications are hereby incorporated byreference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an active matrix display device inwhich a thin film luminescent element such as an EL(electroluminescence) element or LED (light emitting diode) element,that emits light by application of a driving current to an organicsemiconductor film, is driven and controlled by a thin film transistor(hereinafter referred to as a TFT).

2. Description of the Related Art

Active matrix display devices using current-controlled luminescentelements such as EL elements or LED elements have been disclosed. Sinceluminescent elements used in display devices of this type areself-luminescent, backlights are not required, unlike in liquid crystaldisplay devices, and the viewing angle dependence is small, all of whichare advantageous.

FIG. 13 is a block diagram of an active matrix display device which usesorganic thin-film EL elements of the charge-injection type as describedabove. In an active matrix display device 1A shown in the drawing, on atransparent substrate 10, a plurality of scanning lines gate, aplurality of data lines sig extending in the direction orthogonal to thedirection of extension of the scanning lines gate, a plurality of commonfeeders com which run parallel to the data lines sig, and a plurality ofpixels 7 which are formed in a matrix by the data lines sig and thescanning lines gate are arrayed. A data side drive circuit 3 and ascanning side drive circuit 4 are formed for data lines sig and scanninglines gate, respectively. Each of the pixels 7 includes a conductioncontrol circuit 50 to which scanning signals are supplied through thescanning line gate and a thin film luminescent element 40 which emitslight in response to picture signals supplied from the data line sigthrough the conduction control circuit 50. In this example, theconduction control circuit 50 includes a first TFT 20 in which scanningsignals are supplied to a gate electrode through the scanning line gate,a storage capacitor cap for retaining picture signals supplied from thedata line sig through the first TFT 20, and a second TFT 30 in whichpicture signals retained by the storage capacitor cap are supplied to agate electrode. The second TFT 30 and the thin film luminescent element40 are connected in series between an opposing electrode op (which willbe described later in detail) and the common feeder con. The thin filmluminescent element 40 emits light in response to a driving currentapplied from the common feeder con when the second TFT 30 is ON, and theemission is retained by the storage capacitor cap for a predeterminedperiod of time.

With respect to the active matrix display device 1A having theconfiguration described above, as shown in FIG. 14 and FIGS. 15(A) and15(B), in any pixel 7, the first TFT 20 and the second TFT 30 are formedusing an island-like semiconductor film. The first TFT 20 has a gateelectrode 21 as a portion of the scanning line gate. In the first TFT20, the data line sig is electrically connected to one of source anddrain regions through a contact hole of a first interlayer insulatingfilm 51, and a drain electrode 22 is electrically connected to theother. The drain electrode 22 extends toward the region in which thesecond TFT 30 is formed, and to this extension, a gate electrode 31 ofthe second TFT 30 is electrically connected through a contact hole ofthe first interlayer insulating film 51. In the second TFT 30, aninterconnecting electrode 35 is electrically connected to one of thesource and drain regions through a contact hole of the first interlayerinsulating film 51, and to the interconnecting electrode 35, a pixelelectrode 41 of the thin film luminescent element 40 is electricallyconnected through a contact hole of a second interlayer insulating film52.

As is clear from the FIG. 14 and FIGS. 15(B) and 15(C), the pixelelectrode 41 is formed independently by pixel 7. On the upper layer sideof the pixel electrode 41, an organic semiconductor film 43 and theopposing electrode op are deposited in that order. Although the organicsemiconductor film 43 is formed by pixel 7, it may be formed in a stripso as to extend over a plurality of pixels 7. As is seen from FIG. 13,the opposing electrode op is formed not only on a display area 11 inwhich pixels 7 are arrayed, but also over substantially the entiresurface of the transparent substrate 10.

Again, in FIG. 14 and FIG. 15(A), to the other one of the source anddrain regions of the second TFT 30, the common feeder con iselectrically connected through a contact hole of the first interlayerinsulating film 51. An extension 39 of the common feeder com is opposedto an extension 36 of the gate electrode 31 of the second TFT 30 withthe first interlayer insulating film 51 as a dielectric filmtherebetween to form the storage capacitor cap.

However, in the active matrix display device 1A, since only the secondinterlayer insulating film 52 is interposed between the opposingelectrode op which faces the pixel electrode 41 and the data line sig onthe same transparent substrate 10, which is different from a liquidcrystal active matrix display device, a large amount of capacitanceparasitizes the data line sig and the load on the data side drivecircuit 3 increases. SUMMARY OF THE INVENTION

Therefore, as shown in FIG. 13, FIG. 14, and FIGS. 16(A), 16(B), and16(C), the present inventor suggests that by providing a thickinsulating film (bank layer bank, a shaded region in which lines thatslant to the left are drawn at a large pitch) between the opposingelectrode op and the data line Big and the like, the capacitance thatparasitizes the data line Big is decreased. At the same time, thepresent inventor suggests that by surrounding a region in which theorganic semiconductor film 43 is formed by the insulating film (banklayer bank), when the organic semiconductor film 43 is formed of aliquid material (discharged liquid) discharged from an ink jet head, thedischarged liquid is blocked by the bank layer bank and the dischargedliquid is prevented from spreading to the sides. However, if such aconfiguration is adopted, a large step bb is formed due to the existenceof the thick bank layer bank, the opposing electrode op formed on theupper layer of the bank layer bank is easily disconnected at the stepbb. If such disconnection of the opposing electrode op occurs at thestep bb, the opposing electrode op in this portion is insulated from thesurrounding opposing electrode op, resulting in a dot defect or linedefect in display. If disconnection of the opposing electrode op occursalong the periphery of the bank layer bank that covers the surface ofthe data side drive circuit 3 and the scanning side drive circuit 4, theopposing electrode op in the display area 11 is completely insulatedfrom a terminal 12, resulting in disenabled display.

Accordingly, it is an object of the present invention to provide anactive matrix display device in which, even when parasitic capacitanceis suppressed by forming a thick insulating film around an organicsemiconductor film, disconnection or the like does not occur in theopposing electrode formed on the upper layer of the thick insulatingfilm.

In order to achieve the object described above, in the presentinvention, an active matrix display device includes a display areahaving a plurality of scanning lines on a substrate, a plurality of datalines extending in the direction orthogonal to the direction ofextension of the scanning lines, and a plurality of pixels formed in amatrix by the data lines and the scanning lines. Each of the pixels isprovided with a thin film luminescent element having a conductioncontrol circuit including a TFT in which scanning signals are suppliedto a gate electrode through the scanning lines, a pixel electrode, anorganic semiconductor film deposited on the upper layer side of thepixel electrode, and an opposing electrode formed at least over theentire surface of the display area on the upper layer side of theorganic semiconductor film. The thin film luminescent element emitslight in response to picture signals supplied from the data linesthrough the conduction control circuit. A region in which the organicsemiconductor film is formed is delimited by an insulating film formedin the lower layer side of the opposing electrode with a thickness thatis larger than that of the organic semiconductor film, and theinsulating film is provided with a discontinuities portion forconnecting the individual opposing electrode sections of the pixels toeach other through a planar section which does not have a step due tothe insulating film.

In the present invention, since the opposing electrode is formed atleast on the entire surface of the display area and is opposed to thedata lines, a large amount of capacitance parasitizes the data lines ifno measures are taken. In the present invention, however, since a thickinsulating film is interposed between the data lines and the opposingelectrode, parasitization of capacitance in the data lines can beprevented. As a result, the load on the data side drive circuit can bedecreased, resulting in lower consumption of electric power or fasterdisplay operation. If a thick insulating film is formed, although theinsulating film may form a large step and disconnection may occur in theopposing electrode formed on the upper layer side of the insulatingfilm, in the present invention, a discontinuities portion is configuredat a predetermined position of the thick insulating film and thissection is planar. Accordingly, the opposing electrodes in theindividual regions are electrically connected to each other through asection formed in the planar section, and even if disconnection occursat a step due to the insulating film, since electrical connection issecured through the planar section which corresponds to thediscontinuities portion of the insulating film, disadvantages resultingfrom disconnection of the opposing substrate do not occur. Therefore, inthe active matrix display device, even if a thick insulating film isformed around the organic semiconductor film to suppress parasiticcapacitance and the like, disconnection does not occur in the opposingelectrode formed on the upper layer of the insulating film, and therebydisplay quality and reliability of the active matrix display device canbe improved.

In the present invention, preferably, the conduction control circuit isprovided with a first TFT in which the scanning signals are supplied toa gate electrode and a second TFT in which a gate electrode is connectedto the data line through the first TFT, and the second TFT and the thinfilm luminescent element are connected in series between a common feederformed independently of the data line and the scanning line for feedinga driving current and the opposing electrode. That is, although it ispossible to configure the conduction control circuit with one TFT and astorage capacitor, in view of an increase in display quality, it ispreferable that the conduction control circuit of each pixel beconfigured with two TFTs and a storage capacitor.

In the present invention, preferably, the insulating film is used as abank layer for preventing the spread of a discharged liquid when theorganic semiconductor film is formed in the area delimited by theinsulating film by an ink jet process. In such a case, the insulatingfilm preferably has a thickness of 1 μm or more.

In the present invention, when the insulating film is formed along thedata lines and the scanning lines such that the insulating filmsurrounds a region in which the organic semiconductor film is formed,the discontinuities portion is formed in a section between the adjacentpixels in the direction of extension of the data lines, between adjacentpixels in the direction of extension of the scanning lines, or adjacentpixels in both directions.

In a different manner from the mode described above, the insulating filmmay be extended along the data lines in a strip, and in such a case, thediscontinuities portion may be formed on at least one end in thedirection of extension.

In the present invention, preferably, in the region in which the pixelelectrode is formed, a region overlapping the region in which theconduction control circuit is formed is covered with the insulatingfilm. That is, preferably, in the region in which the pixel electrode isformed, the thick insulating film is opened only at a planar section inwhich the conduction control circuit is not formed and the organicsemiconductor film is formed only in the interior of this. In such aconfiguration, display unevenness due to layer thickness irregularity ofthe organic semiconductor film can be prevented. In the region in whichthe pixel electrode is formed, in a region overlapping the region inwhich the conduction control circuit is formed, even if the organicsemiconductor film emits light because of a driving current applied fromthe opposing electrode, the light is shaded by the conduction controlcircuit and does not contribute to the display. The driving current thatis applied to the organic semiconductor film in the section which doesnot contribute to the display is a reactive current in terms of display.In the present invention, the thick insulating film is formed in thesection in which such a reactive current should have flowed in theconventional structure, and a driving current is prevented from beingapplied thereat. As a result, the amount of current applied to thecommon feeder can be reduced, and by decreasing the width of the commonfeeder by that amount, the emission area can be increased, and therebydisplay characteristics such as luminance and contrast ratio can beimproved.

In the present invention, preferably, an active matrix display deviceincludes a data side drive circuit for supplying data signals throughthe data lines and a scanning side drive circuit for supplying scanningsignals through the scanning lines in the periphery of the display area;the insulating film is also formed on the upper layer side of thescanning side drive circuit and the data side drive circuit, and theinsulating film is provided with a discontinuities portion forconnecting the opposing electrodes between the display area side and thesubstrate periphery side through a planar section which does not have astep caused by the insulating film at the position between the region inwhich the scanning side drive circuit is formed and the region in whichthe data side drive circuit is formed. In such a configuration, even ifdisconnection of the opposing electrode occurs along the periphery ofthe insulating film that covers the surface of the data side drivecircuit and the scanning side drive circuit, the opposing electrode onthe display area side and the opposing electrode on the substrateperiphery side are connected through the planar section which does nothave a step caused by the insulating film, and the electrical connectionbetween the opposing electrode on the display area side and the opposingelectrode on the substrate periphery side can be secured.

In the present invention, when the insulating film is composed of anorganic material such as a resist film, a thick film can be formedeasily. In contrast, when the insulating film is composed of aninorganic material, an alteration in the organic semiconductor film canbe prevented even if the insulating film is in contact with the organicsemiconductor film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram which schematically shows the general layoutof an active matrix display device as embodiment 1 of the presentinvention.

FIG. 2 is a plan view which shows a pixel included in the active matrixdisplay device shown in FIG. 1.

FIGS. 3(A), 3(B), and 3(C) are sectional views taken along the lineA-A′, the line B-B′, and the line C-C′ of FIG. 2, respectively.

FIG. 4 is a block diagram which schematically shows the general layoutof an active matrix display device as variation 1 of the embodiment 1 ofthe present invention.

FIG. 5 is a plan view which shows a pixel included in the active matrixdisplay device shown in FIG. 4.

FIGS. 6(A), 6(B), and 6(C) are sectional views taken along the lineA-A′, the line B-B′, and the line C-C′ of FIG. 5, respectively.

FIG. 7 is a block diagram which schematically shows the general layoutof an active matrix display device as variation 2 of the embodiment 1 ofthe present invention.

FIG. 8 is a plan view which shows a pixel included in the active matrixdisplay device shown in FIG. 7.

FIGS. 9(A), 9(B), and 9(C) are sectional views taken along the lineA-A′, the line B-B′, and the line C-C′ of FIG. 8, respectively.

FIG. 10 a block diagram which schematically shows the general layout ofan active matrix display device as embodiment 2 of the presentinvention.

FIG. 11 is a plan view which shows a pixel included in the active matrixdisplay device shown in FIG. 10.

FIGS. 12(A), 12(B), and 12(C) are sectional views taken along the lineA-A′, the line B-B′, and the line C-C′ of FIG. 11, respectively.

FIG. 13 is a block diagram which schematically shows the general layoutof an active matrix display device as a comparative example with respectto the conventional device and a device in accordance with the presentinvention.

FIG. 14 is a plan view which shows a pixel included in the active matrixdisplay device shown in FIG. 13.

FIGS. 15(A), 15(B), and 15(C) are sectional views taken along the lineA-A′, the line B-B′, and the line C-C′ of FIG. 14, respectively.

FIGS. 16(A), 16(B), and 16(C) are other sectional views taken along theline A-A′, the line B-B′, and the line C-C′ of FIG. 14, respectively.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention will be described with reference tothe drawings. In the following description, the same reference numeralsare used for the elements which are the same as those described in FIG.13 through FIG. 16(C).

Embodiment 1 (General Configuration)

FIG. 1 is a block diagram which schematically shows the general layoutof an active matrix display device. FIG. 2 is a plan view which shows apixel included in the device shown in FIG. 1. FIGS. 3(A), 3(B), and 3(C)are sectional views taken along the line A-A′, the line B-B′, and theline C-C′ of the FIG. 2, respectively.

In an active matrix display device 1 shown in FIG. 1, the centralsection of a transparent substrate 10 as a base is defined as a displayarea 11. In the periphery of the transparent substrate 10, a data sidedrive circuit 3 for outputting picture signals is formed on the end ofdata lines sig, and a scanning side drive circuit 4 is formed on the endof scanning lines gate. In the drive circuits 3 and 4, complementaryTFTs are configured by n-type TFTs and p-type TFTs, and thecomplementary TFTs constitute a shift register circuit, a level shiftercircuit, an analog switch circuit, and the like. In the display area 11,in a manner similar to that in the active matrix substrate in the liquidcrystal active matrix display device, on the transparent substrate 10, aplurality of scanning lines gate, a plurality of data lines sigextending in the direction orthogonal to the direction of extension ofthe scanning lines gate, and a plurality of pixels 7 which are formed ina matrix by the data lines sig and the scanning lines gate are arrayed.

Each of the pixels 7 includes a conduction control circuit 50 to whichscanning signals are supplied through the scanning line gate and a thinfilm luminescent element 40 which emits light in response to picturesignals supplied from the data line sig through the conduction controlcircuit 50. In the example shown here, the conduction control circuit 50includes a first TFT 20 in which scanning signals are supplied to a gateelectrode through the scanning line gate, a storage capacitor cap forretaining picture signals supplied from the data line sig through thefirst TFT 20, and a second TFT 30 in which picture signals retained bythe storage capacitor cap are supplied to a gate electrode. The secondTFT 30 and the thin film luminescent element 40 are connected in seriesbetween an opposing electrode op (which will be described later indetail) and a common feeder com.

With respect to the active matrix display device 1 having theconfiguration described above, as shown in FIG. 2 and FIGS. 3(A) and3(B), in any pixel 7, the first TFT 20 and the second TFT 30 are formedusing an island-like semiconductor film (silicon film).

The first TFT 20 has a gate electrode 21 as a portion of the scanningline gate. In the first TFT 20, the data line sig is electricallyconnected to one of source and drain regions through a contact hole of afirst interlayer insulating film 51, and a drain electrode 22 iselectrically connected to the other. The drain electrode 22 extendstoward the region in which the second TFT 30 is formed, and to thisextension, a gate electrode 31 of the second TFT 30 is electricallyconnected through a contact hole of the first interlayer insulating film51.

To one of source and drain regions of the second TFT 30, aninterconnecting electrode 35 simultaneously formed with the data linesig is electrically connected through a contact hole of the firstinterlayer insulating film 51, and to the interconnecting electrode 35,a transparent pixel electrode 41 composed of an ITO film of the thinfilm luminescent element 40 is electrically connected through a contacthole of a second interlayer insulating film 52.

As is clear from FIG. 2 and FIGS. 3(B) and 3(C), the pixel electrode 41is independently formed by pixel 7. On the upper layer side of the pixelelectrode 41, an organic semiconductor film 43 composed of polyphenylenevinylene (PPV) or the like and the opposing electrode op composed of ametal film such as lithium-containing aluminum or calcium are depositedin that order to form the thin film luminescent element 40. Although theorganic semiconductor film 43 is formed in each pixel 7, it may beformed in a strip so as to extend over a plurality of pixels 7. Theopposing electrode op is formed on the entire display area 11 and in aregion excluding the periphery of a portion in which terminals 12 of thetransparent substrate 10 are formed. The terminals 12 include a terminalof the opposing electrode op which is connected to wiring (not shown inthe drawing) simultaneously formed with the opposing electrode op.

Additionally, for the thin film luminescent element 40, a structure inwhich luminous efficiency (hole injection efficiency) is increased byproviding a hole injection layer, a structure in which luminousefficiency (electron injection efficiency) is increased by providing anelectron injection layer, or a structure in which both a hole injectionlayer and an electron injection layer are formed, may be employed.

Again, in FIG. 2 and FIG. 3(A), to the other one of source and drainregions of the second TFT 30, the common feeder con is electricallyconnected through a contact hole of the first interlayer insulating film51. An extension 39 of the common feeder con is opposed to an extension36 of the gate electrode 31 of the second TFT 30 with the firstinterlayer insulating film 51 as a dielectric film therebetween to formthe storage capacitor cap.

As described above, in the active matrix display device 1, when thefirst TFT 20 is ON by being selected by scanning signals, picturesignals from the data line sig are applied to the gate electrode 31 ofthe second TFT 30 through the first TFT 20, and at the same time,picture signals are stored in the storage capacitor cap through thefirst TFT 20. As a result, when the second TFT 30 is ON, a voltage isapplied with the opposing electrode op and the pixel electrode 41serving as a negative pole and a positive pole, respectively, and in theregion in which the applied voltage exceeds the threshold voltage, acurrent (driving current) applied to the organic semiconductor film 43sharply increases. Accordingly, the luminescent element 40 emits lightas an electroluminescence element or an LED element, and light of theluminescent element 40 is reflected from the opposing electrode op andis emitted after passing through the transparent pixel electrode 41 andthe transparent substrate 10. Since the driving current for emittinglight as described above flows through a current path composed of theopposing electrode op, the organic semiconductor film 43, the pixelelectrode 41, the second TFT 30, and the common feeder con, when thesecond TFT 30 is OFF, the driving current stops flowing. However, in thegate electrode of the second TFT 30, even if the first TFT 20 is OFF,the storage capacitor cap maintains an electric potential that isequivalent to the picture signals, and thereby the second TFT 30 remainsON. Therefore, the driving current continues to be applied to theluminescent element 40, and the pixel stays illuminated. This state ismaintained until new image data are stored in the storage capacitor capand the second TFT 30 is OFF.

(Structure of Bank Layer)

In the active matrix display device 1 having the configuration describedabove, in this embodiment, in order to prevent the data lines sig frombeing parasitized with a large amount of capacitance, as shown in FIG.1, FIG. 2, and FIGS. 3(A), 3(B), and 3(C), a thick insulating filmcomposed of a resist film or polyimide film (bank layer bank, a shadedregion in which lines that slant to the left are drawn at a large pitch)is provided along the data lines sig and the scanning lines gate, andthe opposing electrode op is formed on the upper layer side of the banklayer bank. Thereby, since the second interlayer insulating film 52 andthe thick bank layer bank are interposed between the data line sig andthe opposing electrode op, capacitance that parasitizes the data linesig is significantly reduced. Therefore, the load on the drive circuits3 and 4 can be decreased and lower consumption of electric power orfaster display operation can be achieved.

As shown in FIG. 1, the bank layer bank (diagonally shaded region) isalso formed in the periphery of the transparent substrate 10 (a regionexternal to the display area 11). Accordingly, both the data side drivecircuit 3 and the scanning side drive circuit 4 are covered with thebank layer bank. The opposing electrode op is required to be formed atleast on the display area 11, and is not required to be formed in drivecircuit regions. However, since the opposing electrode op is generallyformed by mask-sputtering, alignment accuracy is low and the opposingelectrode op may sometimes overlap drive circuits. However, in thisembodiment, even if the opposing electrode op overlaps the region inwhich the drive circuits are formed, the bank layer bank is interposedbetween the lead layer of the drive circuits and the opposing electrodeop. Therefore, the parasitization of capacitance in the drive circuits 3and 4 can be prevented, and thereby the load on the drive circuits 3 and4 can be decreased and lower consumption of electric power or fasterdisplay operation can be achieved.

Further, in this embodiment, in the region in which the pixel electrode41 is formed, in a region in which the conduction control circuit 50overlaps the interconnecting electrode 35, the bank layer bank is alsoformed. Therefore, the organic semiconductor film 43 is not formed inthe overlapping region with the interconnecting electrode 35. That is,since the organic semiconductor film 43 is formed only in the planarsection in the region in which the pixel electrode 41 is formed, theorganic semiconductor film 43 is formed at a given thickness and displayunevenness does not occur. If there is no bank layer bank in theoverlapping region with the interconnecting electrode 35, a drivingcurrent flows between this section and the opposing electrode op and theorganic semiconductor film 43 emits light. However, the light issandwiched between the interconnecting electrode 35 and the opposingelectrode op, is not emitted externally, and does not contribute todisplay. Such a driving current which flows in the section that does notcontribute to display is a reactive current in view of display. However,in this embodiment, the bank layer bank is formed in the section inwhich such a reactive current should have flowed in the conventionalstructure, and a driving current is prevented from being appliedthereat; a useless current can thereby be prevented from flowing throughthe common feeder con. Therefore, the width of the common feeder con canbe decreased by that amount. As a result, the emission area can beincreased, and thereby display characteristics such as luminance andcontrast ratio can be improved.

Moreover, in this embodiment, since the bank layer bank is formed alongthe data lines sig and the scanning lines gate, any pixel 7 issurrounded by the thick bank layer bank. Thereby, if no measures aretaken, the opposing electrode op of each pixel 7 is connected to theopposing electrode op of the adjacent pixel 7 by climbing over the banklayer bank. In this embodiment, however, a discontinuities portion offis formed in the bank layer bank at the section corresponding to asection between the adjacent pixels 7 in the direction of extension ofthe data line sig. A discontinuities portion off is also formed in thebank layer bank at the section corresponding to a section between theadjacent pixels 7 in the direction of extension of the scanning linegate. Further, a discontinuities portion off is also formed in the banklayer bank at each end of the data lines sig and the scanning lines gatein each of the directions of extension.

Since such a discontinuities portion off does not have the thick banklayer bank, it is a planar section which does not have a large step dueto the bank layer bank and the opposing electrode op formed in thissection does not suffer from disconnection. Thereby, the opposingelectrode 7 of each pixel 7 is securely connected to each other throughthe planar section which does not have a step due to the bank layerbank. Therefore, even if a thick insulating layer (bank layer bank) isformed around the pixel 7 to suppress parasitic capacitance and thelike, disconnection does not occur in the opposing electrode op formedon the upper layer of the thick insulating film (bank layer bank).

Moreover, the bank layer bank formed on the upper layer side of thescanning side drive circuit 4 and the data side drive circuit 3 isprovided with a discontinuities portion off at the position between theregion in which the scanning side drive circuit 4 is formed and theregion in which the data side drive circuit 3 is formed. Thereby, theopposing electrode op on the side of the display area 11 and theopposing electrode op in the periphery of the substrate are connectedthrough the discontinuities portion off of the bank layer bank, and thisdiscontinuities portion is also a planar section which does not have astep due to the bank layer bank. Accordingly, since the opposingelectrode op formed in the discontinuities portion off is notdisconnected, the opposing electrode op on the side of the display area11 and the opposing electrode op in the periphery of the substrate aresecurely connected through the discontinuities portion off of the banklayer bank, and the terminals 12 that are wired and connected to theopposing electrode op in the periphery of the substrate and the opposingelectrode op in the display area 11 are securely connected.

If the bank layer bank is formed of a black resist, the bank layer bankfunctions as a black matrix, resulting in improvement in display qualitysuch as contrast ratio. That is, in the active matrix display device 1of this embodiment, since the opposing electrode op is formed over theentire surface of the pixel 7 on the face side of the transparentsubstrate 10, reflected light from the opposing electrode op decreasescontrast ratio. However, if the bank layer bank that functions as apreventer of parasitic capacitance is composed of a black resist, thebank layer bank also functions as a black matrix and shades thereflected light from the opposing electrode op, resulting in improvementin contrast ratio.

(Method for Fabricating Active Matrix Display Device)

Since the bank layer bank formed as described above is configured so asto surround the region in which the organic semiconductor film 43 isformed, in the fabricating process of the active matrix display device,when the organic semiconductor film 43 is formed of a liquid material(discharged liquid) discharged from an ink jet head, the bank layer bankblocks the discharged liquid and prevents the discharged liquid fromspreading to the sides. In the method for fabricating the active matrixdisplay device 1 described below, since the steps up to the fabricationof the first TFT 20 and the second TFT 30 on the transparent substrate10 are substantially the same as those for fabricating the active matrixsubstrate of the liquid crystal active matrix display device 1, theoutline will be briefly described with reference to FIGS. 3(A), 3(B),and 3(C).

First, on the transparent substrate 10, as required, a protective film(not shown in the drawing) composed of a silicon oxide film having athickness of approximately 2,000 to 5,000 angstroms is formed by aplasma CVD process using TEOS (tetraethoxysilane) or oxygen gas as asource gas, and then on the surface of the protective film, asemiconductor film composed of an amorphous silicon film having athickness of approximately 300 to 700 angstroms is formed by a plasmaCVD process. Next, the semiconductor film composed of an amorphoussilicon film is subjected to a crystallization step such aslaser-annealing or solid phase epitaxy to crystallize the semiconductorfilm into a poly-silicon film.

Next, the island-like semiconductor film is formed by patterning thesemiconductor film, and on the surface thereof, a gate insulating film27 composed of a silicon oxide film or nitride film having a thicknessof approximately 600 to 1,500 angstroms is formed by a plasma CVDprocess using TEOS (tetraethoxysilane) or oxygen gas as a source gas.

Next, a conductive film composed of a metal film such as aluminum,tantalum, molybdenum, titanium, or tungsten is formed by sputtering andis then patterned to form gate electrodes 21 and 31, and an extension 36of the gate electrode 31 (gate electrode formation step). In this step,scanning lines gate are also formed.

In this state, source and drain regions are formed in a self-alignedmanner with respect to the gate electrodes 21 and 31 by implantinghigh-concentration phosphorus ions. The section in which impurities arenot implanted becomes a channel region.

Next, after the first interlayer insulating film 51 is formed, theindividual contact holes are formed. Then, the data line sig, the drainelectrode 22, the common feeder con, the extension 39 of the commonfeeder con, and the interconnecting electrode 35 are formed. As aresult, the first TFT 20, the second TFT 30, and the storage capacitorcap are formed.

Next, the second interlayer insulating film 52 is formed, and a contacthole is formed in the interlayer insulating film at the sectioncorresponding to the interconnecting electrode 35. Then, after an ITOfilm is formed on the entire surface of the second interlayer insulatingfilm 52, by patterning, the pixel electrode 41 that is electricallyconnected to the source/drain region of the second TFT 30 through thecontact hole is formed in each pixel 7.

Next, after a resist layer is formed on the surface side of the secondinterlayer insulating film 52, the resist is patterned so as to remainalong the scanning line gate and the data line sig to form the banklayer bank. A discontinuities portion off is formed at a predeterminedsection of the bank layer bank. At this stage, the resist section to beleft along the data line sig is formed broadly so as to cover the commonfeeder com. As a result, the region in which the organic semiconductorfilm 43 of the luminescent element 40 is to be formed is surrounded bythe bank layer bank.

Next, in the region delimited in a matrix by the bank layer bank, theindividual organic semiconductor films 43 corresponding to R, G, and Bare formed using an ink jet process. To this end, a liquid material(precursor) for constituting the organic semiconductor film 43 isdischarged from an ink jet head to the interior region of the bank layerbank, and is fixed in the interior region of the bank layer bank to formthe organic semiconductor film 43. The bank layer bank is waterrepellent because it is composed of a resist. In contrast, since theprecursor of the organic semiconductor film 43 uses a hydrophilicsolvent, even if there is a discontinuities portion off in the banklayer bank that delimits the region in which the organic semiconductorfilm 43 is formed, since such a discontinuities portion off is narrow,the region in which the organic semiconductor film 43 is applied issecurely defined by the bank layer bank and spreading to the adjacentpixel 7 does not occur. Therefore, the organic semiconductor film 43,etc., can be formed only within the predetermined region. In this step,since the precursor discharged from the ink jet head swells to athickness of approximately 2 to 4 μm under the influence of surfacetension, the bank layer bank must have a thickness of approximately 1 to3 μm. The fixed organic semiconductor film 43 has a thickness ofapproximately 0.05 to 0.2 μm. Additionally, when the barrier of the banklayer bank has a height of 1 μm or more, even if the bank layer bank isnot water repellent, the bank layer bank functions satisfactorily as abarrier. By forming such a thick bank layer bank, the region in whichthe organic semiconductor film 43 is formed can be defined when the film43 is formed by an application process instead of the ink jet process.

Then, the opposing electrode op is formed substantially on the entiresurface of the transparent substrate 10.

In accordance with the fabrication method described above, since theindividual organic semiconductor films 43 corresponding to R, G, and Bcan be formed in the predetermined region using the ink jet process, thefull color active matrix display device 1 can be fabricated with highproductivity.

Additionally, although TFTs are also formed in the data side drivecircuit 3 and the scanning side drive circuit 4 shown in FIG. 1, theTFTs are formed entirely or partially repeating the steps of forming theTFTs in the pixel 7 described above. Therefore, TFTs included in thedrive circuits are formed between the same layers as those of the TFTsof the pixel 7. With respect to the first TFT 20 and the second TFT 30,both may be n-type or p-type, or one may be n-type and the other may bep-type. In any combination, since TFTs can be formed in a known manner,description thereof will be omitted.

Variation 1 of Embodiment 1

FIG. 4 is a block diagram which schematically shows the general layoutof an active matrix display device. FIG. 5 is a plan view which shows apixel included in the device shown in FIG. 4. FIGS. 6(A), 6(B), and 6(C)are sectional views taken along the line A-A′, the line B-B′, and theline C-C′ of FIG. 5, respectively. Since this embodiment has basicallythe same configuration as that of embodiment 1, the same referencenumerals are used for the parts that are the same as those of embodiment1, and detailed description thereof will be omitted.

As shown in FIG. 4, FIG. 5, and FIGS. 6(A), 6(B), and 6(C), in an activematrix display device 1 of this embodiment, a thick insulating filmcomposed of a resist film (bank layer bank, a shaded region in whichlines that slant to the left are drawn at a large pitch) is alsoprovided along the data lines sig and the scanning lines gate, and theopposing electrode op is formed on the upper layer side of the banklayer bank. Thereby, since the second interlayer insulating film 52 andthe thick bank layer bank are interposed between the data line sig andthe opposing electrode op, the capacitance that parasitizes the dataline sig is significantly reduced. Therefore, the load on the drivecircuits 3 and 4 can be decreased and lower consumption of electricpower or faster display operation can be achieved.

The bank layer bank (diagonally shaded region) is also formed in theperiphery of the transparent substrate 10 (a region external to thedisplay area 11). Accordingly, both the data side drive circuit 3 andthe scanning side drive circuit 4 are covered with the bank layer bank.Even if the opposing electrode op overlaps the region in which the drivecircuits are formed, the bank layer bank is interposed between thewiring layer of the drive circuits and the opposing electrode op.Therefore, the parasitization of capacitance in the drive circuits 3 and4 can be prevented, and thus the load on the drive circuits 3 and 4 canbe decreased and lower consumption of electric power or faster displayoperation can be achieved.

Further, in this embodiment, in the region in which the pixel electrode41 is formed, in a region in which the conduction control circuit 50overlaps the interconnecting electrode 35, the bank layer bank is alsoformed, and thereby a useless reactive current can be prevented fromflowing. Therefore, the width of the common feeder con can be decreasedby that amount.

Moreover, in this embodiment, since the bank layer bank is formed alongthe data lines sig and the scanning lines gate, any pixel 7 issurrounded by the bank layer bank. Therefore, since the individualorganic semiconductor films 43 corresponding to R, G, and B can beformed in the predetermined region using an ink jet process, the fullcolor active matrix display device 1 can be fabricated with highproductivity.

Moreover, a discontinuities portion off is formed in the bank layer bankat the section corresponding to a section between the adjacent pixels 7in the extending direction of the scanning lines gate. A discontinuitiesportion off is also formed in the bank layer bank at each end of thedata lines sig and the scanning lines gate in each of the extendingdirections. Further, the bank layer bank formed on the upper layer sideof the scanning side drive circuit 4 and the data side drive circuit 3is provided with a discontinuities portion off at the position betweenthe region in which the scanning side drive circuit 4 is formed and theregion in which the data side drive circuit 3 is formed. Accordingly,the opposing electrodes op are securely connected to each other througha planar section (discontinuities portion off) which does not have astep due to the bank layer bank, and disconnection does not occur.

Variation 2 of Embodiment 1

FIG. 7 is a block diagram which schematically shows the general layoutof an active matrix display device. FIG. 8 is a plan view which shows apixel included in the device shown in FIG. 7. FIGS. 9(A), 9(B), and 9(C)are sectional views taken along the line A-A′, the line B-B′, and theline C-C′ of FIG. 8, respectively. Since this embodiment has basicallythe same configuration as that of embodiment 1, the same referencenumerals are used for the parts that are the same as those of embodiment1, and detailed description thereof will be omitted.

As shown in FIG. 7, FIG. 8, and FIGS. 9(A), 9(B), and 9(C), in an activematrix display device 1 of this embodiment, a thick insulating filmcomposed of a resist film (bank layer bank, a shaded region in whichlines that slant to the left are drawn at a large pitch) is alsoprovided along the data lines sig and the scanning lines gate, and theopposing electrode op is formed on the upper layer side of the banklayer bank. Thereby, since the second interlayer insulating film 52 andthe thick bank layer bank are interposed between the data line sig andthe opposing electrode op, the capacitance that parasitizes the dataline sig is significantly reduced. Therefore, the load on the drivecircuits 3 and 4 can be decreased and lower consumption of electricpower or faster display operation can be achieved.

The bank layer bank (diagonally shaded region) is also formed in theperiphery of the transparent substrate 10 (a region external to thedisplay area 11). Accordingly, both the data side drive circuit 3 andthe scanning side drive circuit 4 are covered with the bank layer bank.Even if the opposing electrode op overlaps the region in which the drivecircuits are formed, the bank layer bank is interposed between thewiring layer of the drive circuits and the opposing electrode op.Therefore, the parasitization of capacitance in the drive circuits 3 and4 can be prevented, and thus the load on the drive circuits 3 and 4 canbe decreased and lower consumption of electric power or faster displayoperation can be achieved.

Further, in this embodiment, in the region in which the pixel electrode41 is formed, in a region in which the conduction control circuit 50overlaps the interconnecting electrode 35, the bank layer bank is alsoformed, and thereby a useless reactive current can be prevented fromflowing. Therefore, the width of the common feeder con can be decreasedby that amount.

Moreover, in this embodiment, since the bank layer bank is formed alongthe data lines sig and the scanning lines gate, any pixel 7 issurrounded by the bank layer bank. Therefore, since the individualorganic semiconductor films 43 corresponding to R, G, and B can beformed in the predetermined region using an ink jet process, the fullcolor active matrix display device 1 can be fabricated with highproductivity.

Moreover, a discontinuities portion off is formed in the bank layer bankat the section corresponding to a section between the adjacent pixels 7in the extending direction of the data lines sig. A discontinuitiesportion off is also formed in the bank layer bank at each end of thedata lines sig and the scanning lines gate in each of the extendingdirections. Further, the bank layer bank formed on the upper layer sideof the scanning side drive circuit 4 and the data side drive circuit 3is provided with a discontinuities portion off at the position betweenthe region in which the scanning side drive circuit 4 is formed and theregion in which the data side drive circuit 3 is formed. Accordingly,the opposing electrodes op are securely connected to each other througha planar section (discontinuities portion off) which does not have astep due to the bank layer bank, and disconnection does not occur.

Embodiment 2

FIG. 10 is a block diagram which schematically shows the general layoutof an active matrix display device. FIG. 11 is a plan view which shows apixel included in the device shown in FIG. 10. FIGS. 12(A), 12(B), and12(C) are sectional views taken along the line A-A′, the line B-B′, andthe line C-C′ of FIG. 11, respectively. Since this embodiment basicallyhas the same configuration as that of embodiment 1, the same referencenumerals are used for the parts that are the same as those of embodiment1, and detailed description thereof will be omitted.

As shown in FIG. 10, FIG. 11, and FIGS. 12(A), 12(B), and 12(C), in anactive matrix display device 1 of this embodiment, a thick insulatingfilm composed of a resist film (bank layer bank, a shaded region inwhich lines that slant to the left are drawn at a large pitch) is formedin a strip along the data lines sig, and the opposing electrode op isformed on the upper layer side of the bank layer bank. Thereby, sincethe second interlayer insulating film 52 and the thick bank layer bankare interposed between the data line sig and the opposing electrode op,the capacitance that parasitizes the data line sig is significantlyreduced. Therefore, the load on the drive circuits 3 and 4 can bedecreased and lower consumption of electric power or faster displayoperation can be achieved.

The bank layer bank (diagonally shaded region) is also formed in theperiphery of the transparent substrate 10 (a region external to thedisplay area 11). Accordingly, both the data side drive circuit 3 andthe scanning side drive circuit 4 are covered with the bank layer bank.Even if the opposing electrode op overlaps the region in which the drivecircuits are formed, the bank layer bank is interposed between thewiring layer of the drive circuits and the opposing electrode op.Therefore, the parasitization of capacitance in the drive circuits 3 and4 can be prevented, and thus the load on the drive circuits 3 and 4 canbe decreased and lower consumption of electric power or faster displayoperation can be achieved.

Moreover, in this embodiment, since the bank layer bank is formed alongthe data lines sig, the individual organic semiconductor films 43corresponding to R, G, and B can be formed in a strip in the regiondelimited in a strip by the bank layer bank using an ink jet process.Thereby, the full color active matrix display device 1 can be fabricatedwith high productivity.

Moreover, the bank layer bank is provided with a discontinuities portionoff at each end of the data lines sig in the extending direction.Thereby, the opposing electrode op of each pixel 7 is connected to theopposing electrode op of the adjacent pixel 7 by climbing over the banklayer bank. By tracing the extending direction of the data lines sig, itis found that the opposing electrodes op of the individual pixels 7 areconnected to the adjacent row of pixels in the extending direction ofthe scanning lines gate, at the end of the data lines sig, through adiscontinuities portion off (planar section which does not have a stepdue to the bank layer bank). Therefore, the opposing electrodes op ofthe individual pixels 7 are connected to each other through the planarsection which does not have a step due to the bank layer bank, and theopposing electrode op of any pixel 7 is not disconnected.

Other Embodiments

Additionally, when the bank layer bank (insulating film) is composed ofan organic material such as a resist film or a polyimide film, a thickfilm can be easily formed. When the bank layer bank (insulating film) iscomposed of an inorganic material such as a silicon oxide film orsilicon nitride film deposited by a CVD process or SOG process, analteration in the organic semiconductor film 43 can be prevented even ifthe insulating film is in contact with the organic semiconductor film43.

Besides the structure in which the storage capacitor cap is formed bythe common feeder con, the storage capacitor cap may be formed by acapacity line formed in parallel to the scanning line gate.

INDUSTRIAL APPLICABILITY

As descried above, in an active matrix display device in accordance withthe present invention, since a thick insulating film is interposedbetween data lines and opposing electrodes, the parasitization ofcapacitance in the data lines can be prevented. Therefore, the load on adata side drive circuit can be decreased, resulting in lower consumptionof electric power or faster display operation. Additionally, adiscontinuities portion is formed at a predetermined position of thethick insulating film and the section is planar. Accordingly, theopposing electrodes in the individual regions are electrically connectedto each other through a section formed in the planar section, and evenif disconnection occurs at a step due to the insulating film, electricalconnection is secured through the planar section corresponding to thediscontinuities portion of the insulating film. Thereby, even if a thickinsulating film is formed around an organic semiconductor film tosuppress parasitic capacitance or the like, disconnection does not occurin the opposing electrodes formed on the upper layer of the insulatingfilm, and thus display quality and reliability of the active matrixdisplay device can be improved.

1. A light emitting device, comprising: a light emitting elementincluding: a first electrode; a second electrode opposing the firstelectrode; and an organic semiconductor film disposed between the firstelectrode and the second electrode, the organic semiconductor filmemitting light in response to an electric current flowing between thefirst electrode and the second electrode; a control transistor thatcontrols the electric current; an interconnecting electrode electricallyconnected to the control transistor, the interconnecting electrode beingconnected to the first electrode and formed so as not to overlap theorganic semiconductor layer in the light emitting element in plan view;and an electrode insulating film formed between the interconnectingelectrode and the first electrode.
 2. The light emitting deviceaccording to claim 1, the interconnecting electrode being electricallyconnected to the first electrode by a contact hole formed in theelectrode insulating film, and the organic semiconductor film beingformed so as not to overlap the contact hole in plan view.
 3. The lightemitting device according to claim 1, further comprising: an insulativebank layer disposed on the first electrode in a region that overlaps theinterconnecting electrode in plan view.
 4. The light emitting deviceaccording to claim 1, further comprising: a transistor insulating film,the control transistor including: an island-like semiconductor film; anda gate electrode formed on the island-shaped semiconductor film, thetransistor insulating film formed between the gate electrode and theinterconnecting electrode.
 5. The light emitting device according toclaim 3, further comprising: a scanning line; a data line that crossesthe scanning line; an electrical supply line; and an intersectiontransistor disposed at an intersection of the scanning line and the dataline, the intersection transistor being electrically connected to eachof the scanning line and the data line, the control transistor beingelectrically connected to the electrical supply line and having a gateelectrode, and the gate electrode of the control transistor beingelectrically connected to the intersection transistor.
 6. The lightemitting device according to claim 2, further comprising: an insulativebank layer disposed on the first electrode in a region that overlaps theinterconnecting electrode in plan view.
 7. The light emitting deviceaccording to claim 2, the control transistor including: an island-likesemiconductor film; and a gate electrode formed on the island-shapedsemiconductor film; and a transistor insulating film formed between thegate electrode and the interconnecting electrode.
 8. The light emittingdevice according to claim 3, further comprising: a transistor insulatingfilm, the control transistor including: an island-like semiconductorfilm; and a gate electrode formed on the island-shaped semiconductorfilm, the transistor insulating film formed between the gate electrodeand the interconnecting electrode.
 9. The light emitting deviceaccording to claim 2, further comprising: a scanning line; a data linethat crosses the scanning line; an electrical supply line that crossesthe scanning line; and an intersection transistor disposed at anintersection of the scanning line and the data line, the intersectiontransistor being electrically connected to each of the scanning line andthe data line, the control transistor being electrically connected tothe electrical supply line, and being electrically connected to theintersection transistor.
 10. The light emitting device according toclaim 3, further comprising: a scanning line; a data line that crossesthe scanning line; an electrical supply line; and an intersectiontransistor disposed at an intersection of the scanning line and the dataline, the intersection transistor being electrically connected to eachof the scanning line and the data line, the control transistor beingelectrically connected to the electrical supply line, and the gateelectrode of the control transistor being electrically connected to theintersection transistor.
 11. The light emitting device according toclaim 4, further comprising: a scanning line; a data line that crossesthe scanning line; an electrical supply line; and an intersectiontransistor disposed at an intersection of the scanning line and the dataline, the intersection transistor being electrically connected to eachof the scanning line and the data line, the control transistor beingelectrically connected to the electrical supply line, and the gateelectrode of the control transistor being electrically connected to theintersection transistor.